1. Field of Invention
This invention relates generally to introducer sheaths for insertion into a patient's vascular system. In particular, this invention relates to improvements to percutaneous introducer sheaths for introducing guide wires, catheters and medication into the vascular system.
2. Description of the Prior Art
An introducer sheath is used to facilitate the introduction of medical implements such as catheters, guide wires or angioplasty balloons. Typically, a needle is inserted through the patient's skin to puncture a blood vessel. The needle is then withdrawn and is replaced by an elongated pointed dilator carried within a tubular introducer sheath. Upon insertion of the introducer sheath and dilator into the blood vessel, the dilator is withdrawn and replaced by the medical implement to be used in the procedure. The introducer sheath remains in place at the entry into the blood vessel.
Prior art introducer sheaths, intravenous catheters and other catheter-like devices which are designed and intended to penetrate the walls of blood vessels are generally designed to have a smooth outer surface. The purpose of such a smooth surface is to minimize resistance encountered by the catheter or sheath as it is introduced through body tissue and into the blood vessel, and thereby reduce the force required to push the catheter through the skin and through the blood vessel wall.
Examples of prior art patents incorporating the use of a smooth, even outer surface sheath include Sepetka U.S. Pat. No. 4,955,862, Fearnot, et al, U.S. Pat. No. 5,069,674, and Fischell U.S. Pat. No. 5,180,376. Each of these prior art patents discloses the use of a smooth, plastic outer covering or tubular sheath to present a smooth outer surface. This facilitates the introduction of these sheaths into blood vessels.
While the foregoing prior art discloses intravenous catheters and introducer sheaths that may be useful and effective for a reduction of the force necessary to penetrate skin and vascular system tissue, bleeding complications around the catheter have been frequently observed. It is theorized that such bleeding complications may be caused by insufficient sealing of the catheter to the vascular wall at the point of insertion. When the sheath is forced into the vascular wall, the rupturing of the vascular tissue at the point of insertion creates an irregular tear in the vascular wall. Since a smooth outer surface catheter sheath does not mate precisely with the irregular surface of the vascular wound, little interference is provided to the leaking or oozing of blood around the sheath.
One prior art patent, Sharrock U.S. Pat. No. 4,368,730, discloses an intravenous catheter having an irregular outer surface formed by a wire-wound spring guide which surrounds the sheath body. The exposed wires present an irregular outer surface. However, the outer surface formed by the circular cross section wire may present undue resistance to easy passage of the sheath through tissue.